Pulleys

COUPLING, CLUTCHING, AND BRAKING DEVICES
Fig. 1 One method of coupling shafts makes use of gears that can replace chains, pulleys, and friction drives. Its major limitation is the need for adequate center distance. However, an idler can be used for close centers, as shown. This can be a plain pinion or an internal gear.

CONTENTS CONTENTS
C H A P T E R
19
1. Introduction. 2. Types of Pulleys for Flat Belts. 3. Cast Iron Pulleys. 4. Steel Pulleys. 5. Wooden Pulleys. 6. Paper Pulleys. 7. Fast and Loose Pulleys. 8. Design of Cast Iron Pulleys.
.lat Belt Pulleys
19.1 Introduction
The pulleys are used to transmit power from one shaft to another by means of flat belts, V-belts or ropes. Since the velocity ratio is the inverse ratio of the diameters of driving and driven pulleys, therefore the pulley diameters should be carefully selected in order to have a desired velocity ratio.

Flat belts drives can be used for large amount of power transmission and there is no upper limit of distance between the two pulleys. Belt conveyer system is one such example. These drives are efficient at high speeds and they offer quite running. A typical flat belt drive with idler pulley is shown in Fig. 13.2.1. Idler pulleys are used to guide a flat belt in various manners, but do not contribute to power transmission. A view of the flat belt cross section is also shown in the figure.

V - Belt Drives
Among flexible machine elements, perhaps V-belt drives have widest industrial application. These belts have trapezoidal cross section and do not have any joints. Therefore, these belts are manufactured only for certain standard lengths. To accommodate these belts the pulleys have V shaped grooves which makes them relatively costlier. Multiple groove pulleys are available to accommodate number of belts, when large power transmission is required.

Flight controls have advanced considerably throughout the years. In the earliest
biplanes flown by the pioneers flight control was achieved by warping wings
and control surfaces by means of wires attached to the flying controls in
the cockpit. Figure 1.1 clearly shows the multiplicity of rigging and control
wires on an early monoplane. Such a means of exercising control was clearly
rudimentary and usually barely adequate for the task in hand.

Shaft is a common and important machine element. It is a rotating member, in general, has a circular cross-section and is used to transmit power. The shaft may be hollow or solid. The shaft is supported on bearings and it rotates a set of gears or pulleys for the purpose of power transmission. The shaft is generally acted upon by bending moment, torsion and axial force. Design of shaft primarily involves in determining stresses at critical point in the shaft that is arising due to aforementioned loading....

1. Introduction. 2. Types of Pulleys for Flat Belts. 3. Cast Iron Pulleys. 4. Steel Pulleys. 5. Wooden Pulleys. 6. Paper Pulleys. 7. Fast and Loose Pulleys. 8. Design of Cast Iron Pulleys.
.lat Belt Pulleys
19.1 Introduction
The pulleys are used to transmit power from one shaft to another by means of flat belts, V-belts or ropes. Since the velocity ratio is the inverse ratio of the diameters of driving and driven pulleys, therefore the pulley diameters should be carefully selected in order to have a desired velocity ratio.

Circumferences of circles are used in calculating speeds of
rotating machine parts, including drills, reamers, milling cutters,
grinding wheels, gears, and pulleys. These speeds are variously
referred to as surface speed, circumferential speed, and peripheral
speed; meaning for each, the distance that a point on the surface or
circumference would travel in one minute.

In this day and age of ever-shorter time schedules and increasing expectations of productivity gains in every aspect of engineering activity, creative problem solving has become prominent among the most important skills that engineers possess. Unfortunately, in the day-to-day intensity of the search for new engineering solutions, it is easy to lose touch with the foundations of that creativity.

CHAPTER 9
COUPLING, CLUTCHING, AND BRAKING DEVICES
COUPLING OF PARALLEL SHAFTS
Fig. 1 One method of coupling shafts makes use of gears that can replace chains, pulleys, and friction drives. Its major limitation is the need for adequate center distance. However, an idler can be used for close centers, as shown. This can be a plain pinion or an internal gear. Transmission is at a constant velocity and there is axial freedom.
Fig. 2 This coupling consists of two universal joints and a short shaft.

Simple machines, such as the club and oar (examples of the lever), are prehistoric. More complex engines using human power, animal power, water power, wind power and even steam power date back to antiquity. Human power was focused by the use of simple engines, such as the capstan, windlass or treadmill, and with ropes, pulleys, and block and tackle arrangements; this power was transmitted usually with the forces multiplied and the speed reduced. These were used in cranes and aboard ships in Ancient Greece, as well as in mines, water pumps and siege engines in Ancient Rome. The writers of...